Reliability-based design snow loads: II. Reliability assessment and mapping procedures.

Abbie B. Liel, David J. DeBock, James R. Harris, Bruce R. Ellingwood, & Jeannette M. Torrents

Published 2017, SCEC Contribution #7139

This paper describes the development of reliability-targeted ground snow load maps for use in building (roof) design. The proposed procedures aim to ensure that structures designed achieve a target safety index, taken to be 3.0 as defined in the ASCE Standard 7. When applied to the U.S. state of Colorado, the reliability-targeted mapping procedure shows that, to achieve this target reliability index, design ground snow loads may need to be larger or smaller than the 50-year return period load that ASCE 7 currently stipulates for design, depending on the site and winter climate conditions at that site. Sites with larger coefficients of variation in the annual maximum snow load (in Colorado, lower altitude sites) generally need design loads larger than the 50-year values. The paper also advances snow reliability assessment procedures through the proposal of a new model for the ground-to-roof conversion factor needed for quantifying roof snow loads as a function of ground snow loads. Spatial smoothing and altitude-dependent mapping procedures are described.

Liel, A. B., DeBock, D. J., Harris, J. R., Ellingwood, B. R., & Torrents, J. M. (2017). Reliability-based design snow loads: II. Reliability assessment and mapping procedures.. Journal of Structural Engineering, 143(7).